Manual

Model 44D User Guide Issue 3, August 2018
Studio Technologies, Inc. Page 13
anything to pin 3. Do not short pins 3 to pin
1 on the Model 44D’s line output connec-
tors as it will stress the output circuitry.
General Purpose Inputs (GPI)
The Model 44D provides two general-pur-
pose input functions that are referred to
as GPI 1 and GPI 2. These functions allow
transport of the status of relay contacts or
open-collector logic signals. The Model
44D’s GPI inputs use logic circuitry, “pulled
up” to 3.3 volts DC by way of resistors,
which are active whenever they are brought
to their logic low state. While the GPI input
circuitry is protected from over-current and
static discharge (ESD), care should be
taken to minimize the chance that “nasty”
signals can reach them.
The GPI inputs are active only when held
in their low state; they can’t be configured
to change state (“latch”) in response to
a logic pulse or momentary closure. Pins
on a 9-pin female D-subminiature connec-
tor (DE-9F) are used for interfacing with
the GPI inputs and system common con-
nections. This connector is located on the
Model 44D’s back panel. A GPI is only
active when its corresponding pin is con-
nected to system common. GPI 1 is acces-
sible on pin 3 and GPI 2 on pin 4. System
common is available on pins 8 and 9. Refer
to Figure 3 for connection details.
Connections made to the analog line out-
puts will be the same whether the Model
44D has been selected to operate in the
audio interface mode or in the tone genera-
tor mode. In the latter mode a continuous
18 kHz sine-wave tone will be present on
line output channel 1 and a continuous
20 kHz sine-wave tone will be present on
line output channel 2. The nominal level
of both signals will be +4 dBu.
If the Model 44D has been configured to
operate in the tone generator mode the two
GPI inputs will not be active. As such, no
connections should be made to pins 3 and
4 of the 9-pin connector.
General Purpose Outputs
(GPO)
The Model 44D provides two general-
purpose output functions that are referred to
as GPO 1 and GPO 2. These functions pro-
vide contact closures that respond to trigger
signals transported over the Dante input (re-
ceiver) audio paths. The trigger signals are
in the form of high-frequency audio tones
(typically 20 kHz) that travel along with the
normal audio signals. The normally-open
(not shorted) contact closures are isolated
from system common. They are provided by
solid-state relay contacts which are intended
to control low-voltage/low-current DC func-
tions. The contacts are rated for a maximum
Figure 3. GPI, GPO, and Auxiliary DC Output
connections
Pin Function
1 GPO 1-A
2 GPO 2-A
3 GPI 1
4 GPI 2
5
Aux DC Out
6 GPO 1-B
7 GPO 2-B
8 COM
9 COM
Note:
Connector type on Model 44D is a 9-pin
female D-subminiature (DE-9F). Installer
must provide a 9-pin male D-subminiature
(DE-9M). Connector uses 4-40 threaded
inserts for locking with mating plug.